My swivel breech gun has two fifty four cal. barrels, one smooth and one rifled. I have shot some deer with the rifled barrel and thought it would be nice to add a turkey to the smooth barrel. I decided to do some testing to see if I could get an a combination of powder, wad , and shot that would do the job. After trying several combinations I settled on 65 grains of three F powder and a 100 grain powder measure of no. 8 shot. I wanted to use more powder but my 83 year old body couldn't stand the recoil.
The attached pictures will tell the story.
This next pictures is a view from the back side of the paper target. You can see the holes more clearly.
It worked. Eighteen lb. at 20 yds.